Thin Film Transistor (TFT) array based panel display technology is the main stream of nowadays display technologies. This is mainly because the manufacture process of TFT is relatively simple, the process cost is low, and is suitable for massive production. With the development of TFT panel display technology, more and more display driver and other functional modules may be implemented by TFT integrated circuit. Row and column driving circuits, power circuit, photoelectric sensing circuit, and so on, which are manufactured by TFT as the major component, are integrated on a display panel to form a System on Panel (SoP). Compared with a conventional display panel, the SoP display panel has the following advantages. First, the number of peripheral driving chips of the display panel is small, so the number of chip pins and connection lines is small correspondingly. Second, the bezel of a display panel is narrow, so that the module of related display panel looks neat and compact. Third, the working sequence of the display panel's module is simple, and the manufacture cost is low. Fourth, the resolution of the display panel is high. Fifth, the display panel has a high reliability, and thus can be easily manufactured to be a flexible display panel. Sixth, touch-control devices, temperature devices and photoelectric sensing devices are easily integrated on the SoP display panel, so the display panel has a higher added value.
In a traditional display panel, photoelectric sensors are placed separately. Such separately placed photoelectric sensors render the bezel of SoP display panel wide. As a result, advantages of SoP display panel cannot be fully exploited. Although researchers in Japan and Korea have reported some photoelectric sensors implemented by TFT technology, the implementations of these schemes are generally independent to the display panel, and extra control signals are needed, therefore the feasibility of which is low. Therefore, how to implement photoelectric sensing function in the interior or the border of TFT array and how to use the resources of the TFT array reasonably without significantly increasing the complexity of display panel are key points to implement TFT integrated photoelectric sensor.